Working in the garden on vegetables or flowers such as this pink Hellebore provides both mental and physical benefits, researchers say. / USA TODAY

by Julia Savacool, Special for USA TODAY

by Julia Savacool, Special for USA TODAY

Before you head out to the backyard this weekend to begin turning over the soil and planting perfect rows of purple pansies, you might like to know that your gardening efforts are doing more than beautifying the neighborhood: They are actually making you happier and healthier.

If you are a seasoned gardener, you likely can attest to the peacefulness found in gardening. Now, a growing field called horticultural therapy is out to prove the power of nature is more than just urban myth. These therapists, who straddle the world of psychology, ecology and botany, use gardening as a tool to help people cope with issues such as anxiety and depression, as well as physical health conditions like heart disease and post-surgery recovery.

"Horticultural therapy as a treatment for many psychological and physical disorders is a valid and increasingly popular intervention," says Mitchell Hewson, Canada's first registered horticultural therapist who founded the country's largest horticultural therapy program at Homewood Health Center, an addiction recovery and mental health treatment facility in Ontario.

Hewson has used horticultural therapy with people who are suffering from conditions including dementia and eating disorders. "Horticultural therapy stimulates thought, exercises the body and encourages an awareness of the external environment. Moreover, the clients who have benefited from this type of therapy report a renewed desire to live, decreased anxiety and improved self-worth."

Other researchers are hopping on the bandwagon as well. In one ongoing study at the University of Copenhagen, researchers hypothesize that people suffering from chronic stress will see a greater improvement in their condition after spending time in a "healing garden" compared with those who receive traditional cognitive behavioral therapy.

"Research has shown an association between doing activities in natural environments and health, particularly in relation to stress," says researcher Ulrika Stigsdotter. "Our ambition is that our nature-based therapy will get the same or better results as the cognitive behavior therapy group. I personally believe the positive effect will last longer." (The study concludes next spring.)

During the study, participants receive three hours of gardening therapy a day, three days a week, for 10 weeks: They talk their way through their personal problems while working with plants or simply resting and enjoying the green space. Stigsdotter notes that the garden provides both a peaceful and a stimulating environment for participants, who are guided by a team of horticultural therapists and professional gardeners. "At Nacadia, no demands are placed on people - the treatment process is implemented at a pace that suits each individual," says Stigsdotter.

The benefits extend beyond mood: At NYU Langone Medical Center's Rusk Institute of Rehabilitation Medicine, a therapy garden is used to help patients regain mobility after surgery or a stroke. In addition, gardening is a mild form of aerobic activity; in older adults, it can help increase flexibility, hand strength, and eye-hand coordination, says Donna Wang, assistant professor of social work at Long Island University in Brooklyn, N.Y., and whose study on the benefits of gardening for older adults was recently published in the Journal of Housing for the Elderly.

"Each person will benefit differently, based on his or her level of functioning as well as physical ability to garden," Wang says. "A stronger person may be able to do a lot of the work hauling soil and shoveling, while someone with a lower level of functioning may only be able to water the plants." While hitting the gym or taking a walk may reap similar cardiovascular benefits, gardening offers the opportunity to learn a new skill, which may improve cognitive functioning as well, Wang notes.

Horticultural therapists believe that the psychological benefits of gardening can be traced to the key role plants played in humankind's evolution. "You're talking about hundreds of millions of years of history built on surviving and thriving in nature," says Joe Hinds, an environmental psychologist and professor at Canterbury Christ Church University in Kent, England. Hinds became intrigued by the healing powers of nature after working with a program that introduces troubled youth to outdoor activities. "It was clear there was a benefit for these kids," he says. "I wanted to know exactly how it worked." Hinds' recent study on the mental health benefits of therapy gardens was published last winter in the Mental Health Review Journal.

Budding horticulturalists should take note, however: A home garden is not all Zen and no angst: "There is a difference between therapy gardens and personal gardens," says Stigsdotter. "In therapy gardens, you don't have to worry about remembering to water the plants or mow the lawn" because a professional gardener will attend to the tasks that you do not finish. "A private garden may be more demanding."